Town of Hillsborough, California | 403 followers on LinkedIn. Hillsborough is an incorporated town in San Mateo County, California, in the San Francisco Bay Area. Hillsborough is one of the wealthiest communities in America and has the highest income of places in the United States with populations of at least 10,000. It is located 17 miles (27 km) south of San Francisco on the San Francisco Peninsula, bordered by Burlingame to the north, San Mateo to the east, Highlands-Baywood Park to the south, and Interstate 280 to the west.